- February 7: A Sangheili Zealot activates a weapon on Sedra, causing a significant number of human fatalities.
- September 25: A musical event, Believe, takes place at the UNSC Symphony Hall at 1900 hours, and performed by the UNSC's own Symphony Orchestra. It is centered on remembering Master Chief Petty Officer John-117 and his service to the UNSC.
- After November 7: On board the UNSC Forward Unto Dawn, Cortana, showing clear signs of Rampancy, files a report on the history of the Forerunners and Humanity.[note 1]
- The date of Cortana's creation date could be a reference to her best friend, John-117. She was created in November on the 7th, or 117, the month being 11, and the day being 7.
- ↑ This year can be figured out by taking the year Cortana was made in (2549/11/07) and adding seven years. In the Halo Legends episode Origins, Cortana speaks how she is 7 years old.